Electrical crystal contact device



May 20, 1952 E. G. JAMES ETAL I ELECTRICAL; CRYSTAL CONTACT DEVICE Filed May 10. 1950 INVENTORS EMRYS G JAMES REY O. E. LINDELL ATTO R NEY thereof, reference is had Patented May 20, .1952

ELECTRICAL CRYSTAL CONTACT DEVICE Emrys Gwynne James and Aubrey'oscar Edgar Lindell, Wembley, England, tine Research, Inc., Chicago,

of Illinois Application assignors'to Hazel- Ill., a corporation May 10, 1950, Serial No. 161,125

In Great Britain November 15, 1948 5 Claims.

General The present invention is directed to electrical crystal contact devices. More particularly, the invention relates to electrical crystal contact devices of the kind comprising an element of semiconducting crystalline material co-operating with at least two metallic contact members or wires which each makes substantially point contact therewith, the element and the contact members preferably being housed in a suitable protective container.

Electrical crystal contact devices of the type which include two contact members having two contact points in spaced engagement with the surface of the crystalline element are known in the art and are frequently used for amplification of electrical signals. For certain applications of these, devices, such as transistor-type repeaters, the spacing of the points of contact substantially affects the repeater characteristics. Accordingly this spacing must be accurately determined. Heretofore it has been relatively dificult to construct such devices in a manner which lends itself to the use of inexpensive mass-production techniques and yet which provides an accurate predetermined spacing of the points of contact.

It is an object of the present invention, therefore, to provide a new and improved electrical crystal contact device which avoids the abovementioned disadvantage of prior such devices.

It is another object of the invention to provide an electrical crystal contact device which has an accurate spacing between the contact points engaging the semiconducting crystal of the device and yet which is relatively inexpensive to manufacture.

In accordance with a particular form of the invention, an electrical crystal contact device comprises a body of insulating material, and at least a pair of wires supported in substantially parallel relation and with a predetermined substantially uniform spacing therebetween by that body at at least two spaced points along the length of each of the wires. The contact device further includes a resilient member, a terminal, and a crystalline element in engagement with the terminal and maintained in contact by the member in yielding engagement with a small portion of the outer peripheral surface of each of the wires at a position along the length of and intermediate the ends of each of the wires.

For a better understanding of the present invention, together with other and further objects to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring now to the drawing, Fig. 1 is an enlarged perspective view of an electrical crystal contact device in accordance with the present invention; Fig. 2 is a sectional view of the device of Fig. 1 taken along the line 2-2; Fig. 3 is an enlarged perspective view of a crystal contact device in accordance with a modified form of the invention; Fig. 4. is a sectional view taken along the line 44 of Fig. 3; and Figs. 5-7, inclusive, are enlarged perspective views of additional modications of the present invention.

Description of Fig. 1 Contact device Referring now more particularly to Fig. 1 of the drawing, the electrical crystal contact device thereof comprises a body such as a rectangular block I of insulating material such as ceramic or synethic resin plastic. At least a pair of wires 2, 2 are supported in substantially parallel relation and with a predetermined spacing therebetween by the block I at at least two spaced points along the length of each of the wires. An extremely quick and economical way of securing the wires 2, 2 to the block 1 to produce a substantially uniform spacing between the wires comprises winding at least two turns of wire around four adjacent sides of the block and securing at least two of those turns in position on a flat surface 9 of the block by means of small patches 3, 3 of insulating cement. These patches preferably have a small separation therebetween and maybe positioned near opposite edges l0, [0 of the block I. The cement patches 3, 3 preferably engage corresponding spaced points along the length of each of the wires 2, 2. The turns of wire mentioned above are preferably wound on the block I by any suitable coilor grid-winding machine, thus not only assuring a very accurate spacing between convolutions but also accomplishing this operation in a manner which lends itself to inexpensive mass-production techniques. It may be stated, by way of example, that the wires 2, 2 may have a diameter of 0.05 millimeter and that the longitudinal axes thereof are spaced 0.1 millimeter apart. To avoid any discrepancies in pitch which may occur with reference to the few turns near the beginning and the end of a winding, it is preferable to wind more than two turns on the block I. v

All of the turns which were wound on the block I are next severed near the edges l0, l0 and then removed from the block so that only the two wires 2, 2 remain secured thereto by the cement each of the wires, preferably, intermediate thecement patches 3,3. This. crystalline element may comprise a suitable material such. as germae nium and may have a substantially conical tip, as represented in Figs. 1 and 2, for engagement with the intermediate portions of, the wires 2, 2. The crystalline element 4 effectively will have a point of contact with each of the wires 2, 2' and the distance between these two points of contact. on the crystalline element will be slightly less than the distance between the longitudinal axes of the wires. It will be manifest. that this dis.- tance can be accurately determined for a given cone angle: and a diameter of wire..

The crystalline element. 4 is. preferably maintained in a-suitable.protectivecontainer I2. which may have an aperture thereinto receive a. conductive support l3, the-inner end. of which is secured to the crystalline: element. 4.. A. resilient member, such as aleai spring. I4, may besecured to the container 1-2 and arranged to engage one end of the support [-3 to maintain the. crystalline element in yielding engagement. with, two points on the periphery of the wires 2, 2. The member I l may also serve asone of the terminals of the electrical crystal contact device for connecting it in circuit withsuitable-elcctrical apparatus. ;t will be clearthat the-.- cement. patches; 3, 3 on opposite. sides of the points of contact of the crystalline elementAe withthe wires 2, 2. are effective toprevent the forceexerted by the member l2 from: spreading; the. wires 2., 2, thus assuring an: accurate. spacing between. the wires at all times.

Descriptionof Fig; 3: embodiment Referring now. to, Figs. 3. 4. of the. drawin there is represented a. modified. form of. an electrical crystal contact device which is similar to that illustrated in Fig. 1 of the. drawing. Ac-

cordingly, corresponding elements will be identified by the same reference-numerals. Inthe Fig. 3 embodiment of the.invention,.the block offinsulating material. I. is. provided. with. a groove l' of rectangular cross section extending, acrossthe face 9. Thegrooye. l5;isso.dimensionedithatthe opposing side walls. thereof have apredetermined spacing. The wires 2,7 2. are secured in substantially parallel. relation. within. the groove and against. the. opposing side. walls thereof by insulating cement patches. 3,. 3 at. at. least two spaced points along. the. lengths of the. Wires. The crystalline element 4' and. its. conductive support t3 may be. positioned; with relation to the wires 2, 2 as. described; above in .connection with the Fig. 1 device. It. will. be clear. that while the Fig. 3 device. assures accurate predetermined spacing between the. wires 212' of the device, the construction. of the latter does not as readily lend itsel'fto. massrproduction methods as does the device previously described.

Description of Figs. 5 6. and. Z devices.-

It will be understood that the crystalline. element engaging the pair of wires of; the. crystal contact device. may take;- forms other than the conical form considered in connection with the previously described figures of the drawing. For example, Fig. 5 illustrates a crystal contact device employing a crystalline element having a knife edge portion [6. The sharp edge thereof effectively makes a point contact with each of the wires 2, 2.. The longitudinal axes of the wires 2, 2 preferably are substantially perpendicular to the plane of the knife edge portion I6.

Fig. 6 illustrates a modified form of the invention wherein the crystalline element has a substantially hemispherical tip ll, and Fig. '7 represents a still further modification wherein the crystalline element has a thin planar tip 18 engaging the wires 2, 2 in the manner previously described.

From the foregoing descriptions of the various embodiments of the invention, it will be clear that an electrical crystal contact device embodying the present invention is relatively simple in construction, inexpensive to manufacture and yet is characterized by the accurate spacing between the points of. contact of the crystalline element and. the two. wires which are utilized to connect a portion. of the device in an electrical circuit.

there have. been described what are at present considered to be the preferred embodimerits of this invention, it: will. be obvious to those skilled in the. art that various changes and modifications may be made therein without departi'ng from-the invention, and it is, therefore, aimed to cover all such changes and modifications as fall within. the true spirit and scope of the invention.

What is claimed. is:

L.An electrical crystal contact. device comprising; a. body of insulating material; at least a pair: of. wires supported in substantially parallel relation and with a predetermined spacing therebetween by said body at at least two spaced points along the length of each of said wires; a terminal'; and acrystalline element in engagement with said terminal and having a substantially conical tip maintained in contact with a smallportion of the outer peripheral surface of each of said wires at a position. along the length of and intermediate the ends. of each of said wires.

2". electrical crystal contact device comprising' abody of insulating material; at least a pair of wires supported in substantially parallel relation and with a predetermined spacing therebetweenby said body at at least two spaced points; along the length of each of said wires; a terminal; and a crystalline element in engagement with said terminal and having a substantially hemispherical tip maintained in contact with a small portion of the outer peripheral surface" of'each. of said wires at'a position along the length .of. and intermediate the ends of each of said wires.

3.,An electrical crystal contact device comprising a. body ofinsulating material at least a pair of Wires supported in. substantially parallel relationand with a. predetermined spacing, therebetween by said body at. at least two spaced points along, the length of each of. said Wires; a terminal; and. a crystalline element. secured. in electrical engagement with saidterminal andhaving a thin planar tip maintained incontact with a small portion of the outer peripheral surface of each of said wires at a position along. the length of and intermediate the ends of each of said wires.

An electrical crystal contact device comprising. a. body of insulating. material; at least relation and with a predetermined substantially uniform spacing therebetween by said body at at least two spaced points along the length of each of said wires; a resilient member; a terminal; and a crystalline element in engagement with said terminal and maintained by said member in yielding engagement with a small portion of the outer peripheral surface of each of said wires at a position along the length of and intermediate the ends of each of said wires.

5. An electrical crystal contact device comprising: a block of insulating material having a substantially fiat face and a groove of rectangular cross section extending across said face, the opposing side walls of said groove having a predetermined spacing; at least a pair of wires secured in substantially parallel relation within said groove and against said opposing side walls 1 thereof at at least two spaced points along the length of each of said wires; a terminal; and a crystalline element in engagement with said terminal and maintained in contact with a small portion of the outer peripheral surface of each of said wires at a position along the length of and intermediate the ends of each of said wires.

EMRYS GWYNNE' JAMES. AUBREY OSCAR EDGAR LINDELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,503,837 Ohl Apr. 11, 1950 2,524,035 Bardeen et al. Oct. 3, 1950 2,561,109 Giacoletto July 17, 1951 2,561,123 Kurshan July 1'7, 1951 FOREIGN PATENTS Number Country Date 599,341 Great Britain Mar. 10, 1948 

